As well as a balanced diet it is important to exercise to help the body stay healthy and fit.
Children should have an hour of some sort of exercise a day, like walking, running, playing football, skate boarding, dancing or swimming. However, this should to be built up gradually, starting with 30 minutes of exercise a day. You can split the 30 minutes into three, ten minute chunks. This way you can fit it in round your other daily activities.